A Multi-spectral Analysis of Tropical Cyclone Cloud Tops from Combined Satellite and High-Altitude Aircraft Remote Sensing Christopher Velden*, Sarah Monette*, Andrew Heidinger^, Edward Zipser , Peter Black # , Gerald Heymsfield ★
A Multi-spectral Analysis of Tropical Cyclone Cloud Tops from Combined Satellite and High-Altitude Aircraft Remote Sensing
Christopher Velden*, Sarah Monette*, Andrew Heidinger^, Edward Zipser, Peter Black#, Gerald Heymsfield★
*Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin-Madison
#Naval Research Laboratory
^National Oceanic and Atmospheric Administration-National Environmental Satellite, Data, and Information Service, University of Wisconsin-Madison
University of Utah
★National Aeronautics and Space Administration-Goddard Space Flight Center
Comparing ACHA to the Cloud Physics Lidar (CPL) and Scanning High-resolution Interferometer Sounder (S-HIS) aboard the GH:
Comparing Tropical Overshooting Tops (TOTs) to NASA DC-8 Observations in Earl:
At the location of the tail of airplane above while flying over Nadine, ACHA estimates a geometric cloud top height of ~50.5 kft.
ACHA cloud top heights compare well to CPL and S-HIS heights for the GH flight portion over Nadine’s cold convection (circle).
TOTs identified by a CIMSS IR-based algorithm
close to the strong DC-8 updraft profiles in
the eastern eyewall.
DC-8 east to west center-pass. Note vertical velocity spike
with convective tower in the
eastern eyewall ~1916 UTC.
Comparing ACHA to the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP):
The highest CALIOP and CloudSat cloud top estimates from 42 overpasses of western Pacific tropical cyclones are compared to collocated ACHA cloud top heights.
ACHA cloud height product indicates tops in excess of 54 kft (in geometric coordinates) in the region of Nadine, prompting a diversion. The GH is flying at a height of 59 kft in GPS coordinates.
The correlation between the ACHA and CALIOP cloud heights is 0.66.
ACHA and CALIOP cloud top height on August 31, 2010, at 0615 UTC over then Category 4 Hurricane Earl.
By comparison, CALIOP and CLOUDSAT radar-derived cloud heights are correlated at 0.80
ACHA estimated cloud heights match CALIOP reasonably well in the eyewall and outer band.
Converting ACHA to coordinates more often employed by the GH pilots:
The standard coordinates used by GH pilots are in pressure altitude, or “flight level”, which is “the altitude that corresponds to a given value of atmospheric pressure according to the ICAO standard atmosphere.” (AMS Glossary of Meteorology, 2013). ACHA can be used to create flight level cloud top heights by using the following equation:
GOES-13 IR image at 22 UTC on 14 Sept.
This decision to divert emphasizes the necessity to better understand ACHA’s cloud top height accuracies.
It also highlights the discrepancy in standard coordinates for cloud heights used by meteorologists vs. the GH pilots.
What ACHA provided for the 2012 HS3 campaign:
cloud top height in geometric coordinates.
What ACHA can provide for future HS3 campaigns: cloud top height in pressure
Contacts: Chris Velden [email protected]
Sarah Monette [email protected]
Support: NASA Hurricane Science Research Program (HSRP) Grant Number: NNX12AK63G